Ball-bearing screw and nut for lifting jacks and similar devices



July 13, 1939. EL, GQRMLEY 2,166,106

l BALL-BEARING SCREW AND NUT FOR LlFTING JACKS AND SIMILAR DEVICES July 18,'1939.

BALL-BEARING SCREW AND NUT FOR LlFTING JAGKS AND SIMILARy DEVICES F. L. GORMLEY y 2.166.106

Filed Feb. 4, 1938 Figi.

23 8 lllventor:

.FrankL. Gormlfy,v

2 Sheets-Sheet 2 Patented July 18, 1935 UNITED STATES PATENT. OFFICE BALL-BEARIN G SCREW AND NUT FOR LIFTING JACKS AND ISIDIILAR DEVICES tion of Illinois Application February 4, 1938, seriai No. 188,717

7 Claims.

,being helical, said helical portion extending through the inner wall of the nut to permit a small portion of each of said balls to be disposed in said shallow concaved groove of the screw.

The inventionfurther consists in making the helical portion of the cylindrical passage with its center spaced outwardly from the inner wall of the nut so that the balls confined therein cannot, under any condition, escape from said passage, the opening through the wall of the nut having a width less than the diameter of the balls in the endless passage.

The invention further consists in providing a straight portion of the passage extending endwise of said nut and connecting the opposite ends of the helical portion of the passage.

The invention further consists in providing the opposite ends of the nut with removable blocks having openings therethrough forming connections between the straight and-helical portions of the endless passage.

One object of the invention is to provide a practical means for using steel balls to reduce friction between the screw and nut. A

Another object of the invention is the construction of said nut in such a manner that said balls cannot escape from the nut even when said nut is removed from the screw.

A further object is to provide means whereby the angular load will force the balls inwardly into the helical portion of the ball passage in the nut so thatthe load will be carried on the center of said balls.

These objects are attained by the mechanism illustrated in the accompanying drawings.

For ythe purpose of illustrating the invention, one preferred form thereof is illustrated in the drawings, this form4 having been found to give satisfactory and reliable results, although it -is to be understood that the various instrumentalities, of which the invention consists can be varion/sly arranged and organized, and the invention is not limited to the precise arrangementy and organization of these instrumentalities as herein v shown and described except as required by the scope of the appendedclams. Of the drawings Figure 1 represents an elevation, partly in section, of a' lifting jack provided with a ball bearing screw and nut embodying the principles of the present invention.

Figure 2 represents a detail in section of the means for preventing the rotation of the ram.

Figure 3 represents an enlarged section of the ball bearing screw and nut.

Figure 4 represents a transverse section on line 4, 4, on Fig. "3.

Figure 5 represents an enlarge section on line 5, 5, on Fig. 4.

Figure 6 represents a plan of one of the removable blocks of the nut.

Figure 7 represents a side elevation of the same, and

Figure 8 represents an elevation of the inner' end of said removable block.

Similar characters indicate like parts throughout the several gures of the drawings.

-In the drawings, I is the casing of a selflowering lifting jack of usual construction.

In a bearing in said casing I0 is a rotatable shaft II having secured to its outer end a device I2 by which said shaft may be rotated as desired by means of a lever inserted into the socket I3.

As this device I2, I3 forms no part of the present invention it is deemed 'unnecessary to illustrate it in detail.

At the inner end of the shaft II is a bevel pinion I4 which meshes with a bevel gear I5 resting on anti-friction members I6 in the base I1 of the casing I0 as is usual in this type of lifting jacks.

The gear I is keyed to the lower end I8 of a rotatable vscrew I9 extending upwardly in said casing I0 as indicated in Fig. 1 of the drawings.

The screw I9 is provided withv a continuous helical thread in the periphery thereof, said thread being in the form of a shallow concaved groove. .l

Surrounding said screw I9 is a nut 2| having projecting from the lower end thereof a flange 22.

This nut 2| is provided on its inner face with a helical groove 24. This groove 24 is semi-cylindrical with the center 25 thereofspaced outwardly from the inner wall 26l of .the nu`t 2|. f

At one side of the nut 2| is formed a straight cylindrical passage 21 and at opposite ends of this passage are removable blocks 28 having curved openings 29 therethrough, one en d of each continuously through the passage 21, openings 29 y and groove 24.

By having the center of the semi-cylindrical inner walls of the helical groove 24 spaced outwardly from the inner wall 26 of the nut 2| and the outer walls of said groove concentric to another center disposed nearer the outer wall of the nut the opening between the groove 24 and the inner wall 26 of the nut is less than the diameter of the balls 30 contained vwithin said groove 24, consequently these balls 30 are always retained within the groove 24 and cannot be accidentally displaced therefrom even when the nut 2| is removed from the screw.

Less than one half of each ball 30 projects inwardly from the inner wall 26 of the nut 2| and travels in the shallow concaved groove of screw I9.

The balls in the groove 24 have a diameter less than the diameter of the inner semi-cylindrical part of said groove 24, as shown in Fig. 5 of the drawings. v

In order to deposit the balls 30 in the endless passage of the nut 2|, the upper block 28 may be removed and the balls inserted into the upper end of the passage 21 until the groove 24 and passage 21 are lled with balls contacting with each other and then with other balls 3|) positioned in the openings 29 in said block 2,8, the block 28 may bedriven into position in the hole 3| provided therefor in the wall of the nut 2| andsecured in position by headless screws 38 which prevent rotation and end movement of said block 28.

superimposed upon the nut 2| is a cylindrical ram 32 having a groove 33 extending longitudinally of its periphery.

Pivoted at 34 to the casing I9 of the lifting jack is a spring pressed lockingl member 35 which is adapted under normal conditions to enter and coact with said groove 33 to prevent the ram 32 from rotating, while permitting said ram to move vertically when the screw I9 is rotated.

The locking member 35 is shown as one practical means for preventing the rotation of the ram 32, although it must be understood that other means projecting into the groove 33 will serve the same purpose.

The ram 32 may be provided at its lower end with an annular projection 36 threaded into a recess formed in the upper part of the nut 2| as shown in Fig. l of the drawings, thereby connecting the ram 32 tothenut 2|.

The nut 2| is secured at its upper end to the annular threaded projection 36 by means of screws 31, the inner ends of which impinge upon the thread of said projection 36, thus preventing rotation of the ram 32 and nut 2| relatively to each other. f

Preferably the biocks 2s are cyundricai with c their axes coinciding with the center of the helical groove 24, and when driven into the holes 3|, they are locked in position by headless screws 38, one side of each screw 38 being in theI body of the nut 2| and the other side being threaded to the block 38 thus preventing the rotation or displacement of said block.

Preferably the outer periphery of the screw I9 is slightly spaced from the inner wall 26 of the nut 2|, thereby preventing any friction between the periphery of screw I9 and the inner wall 26 of the nut 2|.

The endless ball passage 24, 21 and 29 may be filled with grease or other lubricant, thereby insuring continuous lubrication of the balls 30 as they travel through said endless passage.

By providing this lubrication in the endless passage the ball bearing requires very little, if any, attention after the screw and nut has been assembled.

When the nut 2| has been loaded with the correct number of balls 30, these balls cannot escape from the groove 24 `of the nut 2|, inasmuch as the opening ofthe groove 24 extending through the inner wall 26 of the nut 2| is smaller than the diameter of the balls 30.

Consequently, the groove 24 of the nut, the straight passage 21, and the openings 29 in the blocks 28 will always retain the full complement of balls, if and when the screw I9 is removed from said nut 2|.

It will be noted that in seating the balls 30 in the groove 24 of the nut 2|, over one half of the diameter of each ball is in the groove and this allows theouter portion of the groove 24 I t0 be smaller than the full diameter of the balls 3|I, thus forming a means for holding the balls within the groove 24 under all conditions.

The main portion of the groove 24 is semiv cylindrical with its center at 39, While in order to retain the balls 30 in said groove the remainder of the wall of said groove 24'has its center at 40.

This construction of the groove 24 eifectually prevents the displacement of the balls 30 from said groove.

By thus seating the balls 3|! in the nut 2| in the manner just described, the said balls 30 are permittedy to follow a more natural course when changing direction of rotation from the radius of the thread or groove 2|I in the screw I9 and groove 24 of the nut 2| when passing into one end of the vertical straight passage 21 at one side of said nut or passing from the opposite end of passage 21 into the groove 24.

By thus constructing the ball bearing for the u screw I9 it is possible to use larger size bail bearings without having the nut 2| and the screw I9 out of proportion.

Moreover, the threads or grooves of the screw I9 and-the grooves 24 of the nut 2| are much stronger and will sustain great weight.

It has been found in practice that by the usev manner described and with larger diameter of ball bearings, a lower pitch of thread is possible' in `both screw I9 and nut 2|.

While as shown in the drawings and hereinbefore described the screw I9 is revoluble and prevented from endwise movement. and the nut is non-revoluble but movable endwise, it is selfevident that for some particular Work these operations may be reversed and the nut may be revoluble and immovable endwise while the screw is non-revoluble but movable endwise.

It is obvious, also, that the balls' 30 may be 75 i arcaico inserted into the endless passage of the nut 2i either when removed from the screw i9 or while the screw is inserted therein.

When the screw i9 is being rotated to raise the ram 32 the tendency is for the lower side of the groove in the screw i8 to force the balls toward the upper side of the grooves 2t in the nut 2|.

Consequently, the angular load will :torce the balls into the groove 24 of nut 2i and cause the load to be carried on the center of the balls 38.

As shown in Figs. 6, 7 and 8 the blocks Edera of peculiar construction being round with their outer ends 4l curved to correspond with the periphery of the nut 2l, while portions l2 at the inner end thereof are curved to substantially conform with the inner wall i@ of the nut 2l.

The passage 29 therethrough is so constructed that when the bloclr id is in place, one end will coincide with an end of the straight passage 2l while the other encl'thereo will register with the groove 253.

Between the curved portions i2 the inner end of the block il@ is provided with a curved projecticn @t which entends over the end lill of the passage 2Q where it registers with the groove 2d.

This construction of ball bearing provides for a more 'naturel course oi travel of the balls til when ascending or descending the helical angle or the screw thread The construction of ball bearings as herein shown and described makes a very practical means for' reducing friction between the balls and the surfaces oi the thread in both the screw lil and nut di, this being especially true when heavy loads are encountered and where speed and reduced friction is required.

`While the ball bearing is particularlyadapted i for use in lifting lachs as herein shown and described, it is sell-evident that the saine construction oi ball bearings may be used for a variety of other purposes.. l

It is believed that the operation and many advantages of the invention will be understood without further description.

Having thus described my invention, l claim:

l. The combination of a rotatable screw aren vented from end movement and lea'vingfa widely separated helical concaved groove; a non-rotatable cylindrical nut surrounding said screw and provided with an' endless ball passage, a portion of which is helical and extends through the inner wall of said nut with its center spaced outwardly from said inner wall; a cylindrical block disposed in the cylindrical wall oi said nut having curved openings therein connecting the opposite ends of the helical portion of said passage with the-opposite ends oi' a straight portion of said passage extending lengthwise of said not, the inner end oi said blocl. being provided with a curved groove, the wall of which forms a part of the ball passage; and a continuous train ofy balls confined within said passage with the small portions of said balls disposed within the groove of said screw while moving through the helical portion of the ball passage.

2. The combination of a rotatable screw nreventecl from end movement and having a shallow helical concaved groove separated by wide cylindrical surfaces; a non-rotatable cylindrical nut surrounding said screw and provided with an endless ball passage, a portion of which is hellcal and entends through the inner wall of said nut with its center spaced outwardly from said inner wall; and a continuous train of balls conned within said passage with small portions of said balls coacting with the groove of said screw while moving through the helical portion of said `lng therewith, one of which is non-rotatable while the other is rotatable but immovable eri'd-v wise, said nut being provided with a continuous train of balls adapted to travel endwlse of said` nut irlv an endless ball. passage therein with minor portions of some of said balls disposed within the shallow helical groove of said screw, said ball passage-having a portion thereof helical and extending through the inner wall of the nut17 continuous means being provided on said nut for the entire length of the helical portion of said passage t'o prevent the displacement of said balls from said helical :portion of the ball passage, and

means whereby the halls may be inserted into said ball passage through radial openings in and between the opposite ends oi' the cylindrical wall of said nut.

d. The combination or a screw having a shallow I hellcalgroove and a nut coacting therewith, one of which is non-rotatable while the other is ron tatable but immovable endwise, said nut being provided with a continuous train of balls adapted to travel endwise oi said nut in an endless pasn sage therein with minor portions ci some ol said balls coacting with the shallow helical groove of said screw, a portion of said passage being helical and extending through the inner wall of said nut, said inner wall having continuous on positely disposed curved walls extending toward each other throughout the entire length of the helical portion of said passage to prevent the dis-1 placement of said balls from the helical portion of said passage, the inner wall oi the helical poru tion of said ball passage and said oppositely disposed curved walls being continuous and cone centric to dicrent centers..

5. The combination or a screw having a shallow helical groove and a nut' coactlng therewith, one of which is non-rotatable while the other is rol1 tatable but immovable endwise, said nut having thereinv a continuons ball passage a portion of which is helical and extends through the inner wall of the nut, said nut beine' provided with a continuoustraln oi balls adapted to travel endwise of said nut and some oi the balls in the hellcal portion of said eudlesspassage having minor portions thereof extending into the shallow helical groove oi' said screw, the inner wall of the helical portion of said passage being semi-cylindrical with its center spaced outwardly from the inner cylindrical wall ofthe nut thereby permitting less than half orf each ball to extend into the shallow helical' groove yof said screw, the diameter of the semi-cylindrical wall being greater than the diameter oi said balls, and means on said nut comprising continuous curved projeclength of the helical portion of .the ball passage to prevent the displacement oil-said balls from the helical portion of said passage, the inner walls of said projections being concentric to a tions extending toward each other for the entire i center near the outer cylindrical wail of the nut. 6. Thecombination of a rotatable screw prevented Vfrom end movement and having a hell-,

cal concaved groove; a non-rotatable nut suxrounding said screw and provided with an endless ball passage, a portion oi.' which is helical and extends through the inner wall of saidy nut. the inner wall of said helical portion being semicylindrical with its center spaced outwardly from the'inner wall of said nut; a cylindrical block disposed in the cylindrical wall and between the opposite ends of said nut having curved cylindrical openings therein connecting the opposite .ends of the helical portion of said passage with the opposite ends o f a straight portion of said passage extending lengthwise of said nut; and a continuous train of balls confined within said passage with minor portions of said balls disposed within the shallow helical groove of said screw while moving through the helical portion of the ball passage.

7.,Ihe combination of a rotatable screw prevented from end movement and having a shallow helical concaved groove; a non-rotatable nut surrounding said screw and provided with an endless ball passage, a portion of which is helical and extends through the inner wall ofsaid nut,

the inner part of said passage being semi-cylindrical with its center spaced outwardlyirom said inner wall; insertable and removable blocks near l and between the opposite ends of said nut having curved cylindrical openingsy therethrough connecting the straight and helical portions of said ball passage; and a continuous train of balls conned within said passage with minor portions of the balls when in the helical portion coacting with the shallow helical groove of said screw.

FRANK L. GORMLEY. 

